Apparatus for cutting toothed gears



Apr. 17, 1923. i 1,452,121

F. M. LEWIS APPARATUS FOR CUTTING TOOTHED GEARS Filed Aug. 23, 1920 2 sheets 'sheet 1 mvniumn.

Apr. 17, 1923. 11,452,121

iNV'E NTUR Patented Apr. 17, 1923.

FRANK MICHAEL LEWIS, OF LONDON, ENGLAND.

APPARATUS FOR CUTTING TOOTHED GEARS.

Application filed August 23, 1920. Serial No. 405,332.

This invention relates to the forming of toothed gears having curved or arcuate teeth by a method of generation which involves the cutting of the teeth by means of a cutter rotating in a path extending across the face of the blank about an axis lying in a plane to which the axis of the blank is perpendicular and having a rolling movement relatively to the blank about an axis other than .its axis of rotation.

various methods of generation and various forms of apparatus for carrying out sucn methods have hitherto been proposed, but so far as I am aware they have none of them been entirely satisfactory in practice for the reason that with the methods hitherto proposed it was impossible to obtain a correct tooth form such as is necessary for the proper and efficient intermeshing of the gears to secure smooth and silent running.

It is the object of my invention to obviate the disadvantages of the hitherto known methods of teeth generation and to produce improved apparatus for carrying out my improved method. The accompanying drawings illustrate one convenient form of apparatus for carrying out the invention.

. Figure 1 is a plan.

Figure 2 is a sectional elevation, and

Figure 3 is a diagrammatic view showing one arrangement of cutters.

Figures 4 and 5 areviews illustrating a modified form of cutter.

In carrying my invention into effect in one convenient manner I arrange the work blank a upon a mandril or holder 5 which may be held between centres 0 or be otherwise suitably supported. the work holder being connected by a carrier at or other suitable means to a worm wheel 6, the axis of which is coincident with the axis of the 1 work 'mandril and which is adapted to engage a suitable worm f. The worm wheel and work holder are mounted upon one slide 1 and the worm is mounted upon a second slide h.

The slides carrying the worm and worm wheel are so arranged and are driven at such speeds that the rolling of the blank upon the cutter will occur on the base circle of the blank and by varying the speeds of the respective slides it will be possible to cut a blank of any diameter within the limits of the apparatus or a blank having any base circle, it being known that the base circle is a function of the pitch circle and the pressure angle of tooth so that a gear wheel having a definite pitch circle may have various base circles corresponding with various pressure angles of tooth.

In the example illustrated the slides g and h are connected to blocks 2' which are carried upon a slide 70 adapted to move in a direction transverse to the movement of themain slides, and being carried upon a rotary member Z adapted to be actuated by a worm m or by a toggle link or other suitable mechanism. while means are provided for clamping the slide 70 and in consequence the blocks i in any desired position relatively to the centre of. the rotary member Z so that the speeds oi movement of the slides will be suitably chosen.

With a knowledge of the dimensions of the apparatus and oi the blank to be cut. it is a matter of calculation to decide upon the relative speeds of travel of the slides and in order that the machine may be accurately set for any size blank or any size of base circle without making any separate calculation foreacli case. I may provide a scale in coniunction with an index mark upon the slide 70 so that the latter may be approximately set. I

Ii", for example,

D represents the diameter of the worm wheel e. U

dzthe diameter of the base circle required for the gear to be cut.

Kzthe distance between the centres oi the blocks 7'5, and m the distance betweenthe centre of one block 1'1 and the centre ot the rotary member 7,.

Then

' (Z. a; D

From this equation the necessary setting of the scale can be efiected in order to give the prescribed movements to theslides for any particular gear wheel to be cut.

t For the purpose of indexing the blank.

ried upon the Work mandrilitispreferahle to arrange the indexing,as shownfin connection with the wonnfi carrieclnpon the slide 71,, thls arrangement being rendered possible ,by i the adoption of the Worm and worm Wheel.- It, is 01,: ,t'hlS reason 1 that I tzif n oqe npleypaiw fm and Worm Wheelv track androlling member, but it will be understoodthat a rack and pinion or. any other equiyalentmaybe. adopted- H i Apparatus or arry g n tthe inven e 111 W compri ew ma hin .e h le or i x be formed as an attachment for exist ng .inacl in t s f s t ble, form silt-hi m lling machine l the or th ik but. ,in.,. 2r 1e1i that the earliest orm of QOt shall be produced, Icombine iththe roll; 11g merem i t 1291 the ase circ e me whereby. bo h. fla ks- 93 a h teeth W 1 th .f i t the r iu -l ay be effeete s y employingvtw nnular and m l 9. 1 taming the, to th fe s s 10W .1, & mplei o. d 224 n F ure .3 in ,wbieh eseth ;i terin di m te of eend' 2 0 0? c t in one se of fecesw l .b q elto fl e er e t diameter Pfth o eren m ll 2? f ting h p herstef ects In, pl iii ii rr n ement ew e i t S m e f i ii yte :e QdW- y u i a in le 100. suitably shaped as shown, forexam 1e, in Figures 4; and 5. It willbe seen t at as the;laiigglei'of thelcutterlis less twice the Pre e nele th imm n h n at'ion' occurs, at the point ofthe. tool andthus lhqth'fl asks er" the tooth'are' ermine sane or yeryi, afppron'imatelythe same radius:

. ff ltifw'in be? understood that with he arciange'niein abate "described, the tool, W111 be fifidin? space so that it "will have no inioyeme m m 'f'ro'rn' its movement of rotation. With suitable modifications'but againhim volving the cutting of the tooth faces to the same radius the invention may be a tried to theciltting'of bevel gearstni t e forming of such arcuate bevel gears the maehineinifst be so designed and arranged that the blank rolls'on the cuttersothat each horizontal section rolls on; it's corresponding base circle, that is,"'th'e blank as a vi' hole ro 11s;on'what may be termed; its base time; and again h'othflank's are cut to the same radius.

lVhen dealing with mating gearsThaving arcuate teeth andwintended to run in one direction only,- -it" is sufiicient to cut the engaging faces of the mating gears to the "sam'e'radiusnnd is 'u nnece's's'aryto cutjboth "flanks of" each tooth of" each gear to" the ifer-mation ofracke, in which case 'tlie tool pec ds ofjmovln e'nt of said slide s and is'isi" a EQ-lit 1 indication thej worlz so that the non-cutting teeth Wlll clear the Work. The teeth of such a rack W111 be "'x' ery slight ly"ellip'tical owing to the inclination of the tool, but this will not inter- "feet iri'tli time proper co-operation With .Othe1 ge,ars in which the teeth are similarly arcua te, pr ovided that in forming the gears for meshing with the raclg the cutter isinclined the rolling trackto' the same xt as in ng e. raQ1, ,t Suitable means such as the housing jg", (Figure may b e ad'opted for coyering th W rm f and Wo vWhee 6. son. th t their p a i n. W l othe eli e r'ed ri it ib th cut-ting particles falling thereon and adjusts able stopsq and 1 be provided to limit th'Qd-YQI o the fil de i Q. B w e to d sc irb. W t I; a m f ie we Le r -Eate its i .i v. Appa at s 1. Qui .1 s hel fl Oi? toothedgears' comprisingmeans fOlz-hQltling e li l sie; qu eter Pmratin s sa d bla i' til neerlte .mI Y ble mea f r si ing a, relative rolling movementbetween aid: tt r. a d. said l n s- 11d m ant for Ye r ieet tlwfmqvr m et'. et jf a rl. rtetili arly erab e ,e ee f s .l e to ie y. l i ll lie De Pi 19 .16 .l Qte yfi l.rect ine iil ie- 2, App ra u t l: f rm ng toothe gea s e i i i i bl nk d a lide uppert- M i 2 se blank 1i i tel1e m m e Q1 sai -s d 'as eeed l de thi n 'ai'tra k ere 1 I nsee ee. sa d tell ng inmh n a cutter adapted to; rotate across the: iace of th bl nk. a d e n f l warr n th sl s DEGQSQfi IQQY inelnt dtsaid slides 5. E5 the 1 in? itat ethecieear comprising means for holding" a "blank, a sl de suppe ies said blank. holdin in a worm heelon sai dfslide c onnected' with -said blank holder, 51 Worm Wheel, a slide supporting said' jyorih, a cutter adapted to rotate across'jthe face of the? hla'nk and "varying .Ithe

"relative speeds movement saidislides.

slide supporting blanlt holding means;

a worm when on said slide connectec l: with sa d blank holden. Worm engaging said were] wlieelfa s'lidesupp'ortmmsaid worm.

comprising means for holding .jal blank a fsli'desupportin; jsaiitlblailli holding means,

a wt'rm n heeliotatably mountedon fsaid slide, a carrier connecting said blank hold "m gnate-"with when; at-worm 1:50

engaging said Worm Wheel, a slide carrying said worm, means for reciprocating said slides, a cutter adapted to rotate across the face of the blank and means for varying the relative speeds of movement of said slides.

6. Apparatus for forming toothed gears comprising means for holding a blank, a cutter adapted to operate upon said blank, a slide supporting said blank holding means, a rolling member on said slide connected With said blank holding means, a track engaging said rolling member, a slide supporting said track, a third slide connected With the first mentioned slides and arranged transversely thereto and a rotary member carrying said third mentioned slide.

7. Apparatus for forming toothed gears comprising means for holding a blank, a cutter adapted to operate upon said blank, a slide supporting said blank holding means, a rolling member on said slide connected with said blank holding means, a track engaging said rolling member, a slide supporting said track, a third slide connected with the first mentioned slides and arranged transversely thereto, a rotary member carrying said third mentioned slide and means for varying the points of connection be tween the slides in relation to the centre of said rotary member.

8. Apparatus for forming toothed gear comprising means for holding a blank, a slide supporting said blank holding means, a rolling member on said slide connected With said blank holding means, a track engaging said rolling member, a slide support ing said track, a cutter adapted to operate upon said blank, means for varying the relative speeds of movement of said slides and means for indexing the blank carried by said track.

In testimony whereof I have signed my name to this specification.

FRANK MICHAEL LEWIS. 

